<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    debugger
    function recursivelyCheckEqual (x, ...rest) {
      return Object.is(x, rest[0]) &&
        (rest.length < 2) || recursivelyCheckEqual(...rest)
    }
    console.log(recursivelyCheckEqual(NaN, 33))
  </script>
</body>

</html>
